A Hierarchical Queuing Framework (HQF) provides a hierarchy of queues used by a network device such as a switch. One type of queue hierarchy includes physical, logical, and class levels of queues.
The physical level of the hierarchy is used for policing or shaping the physical interface and can only be identified by class default. In an example system, the logical level of the hierarchy is classified by VLAN ID. At this level, the classification can match on VLAN tag (802.1Q or Inter-Switch Link [ISL]) or 802.1Q tunnel tags (Q-in-Q). Traffic at the class level of the hierarchy is classified by class of service (CoS), IP Precedence, IP differentiated services code point (DSCP), and MPLS EXP bits.
For example, the three levels of queues include 4096 class level queues, 1024 logical level queues, and 1 physical level queue available on each Enhanced Services port. For each logical level queue, there can be 1 to 8 class level queues. These queues can also be serviced by multiple Quality of Service (QoS) functions such as policing, shaping, and sharing.
EtherChannel allows multiple physical Fast Ethernet links to combine into one logical channel to allow load sharing of traffic among the links in the channel as well as redundancy in the event that one or more links in the channel fail. In order to distribute frames across a channel, EtherChannel uses a hash algorithm to reduce part of the binary pattern formed by the addresses in a frame to a numerical value that selects one of the links in the channel. The hash algorithm computes a value that assigns the channel, the user can not control the channel used by a particular flow.